With the continuous development of multimedia technologies, Organic Light Emitting Diodes (OLEDs) used in the organic light emitting display technologies have been increasingly applied to high-performance organic light emitting display devices. As for the organic light emitting display device using the OLEDs, the illumination brightness of the OLED is controlled by the amount of current flowing through the OLED, thereby the effect of showing different grey scales is obtained through different illumination brightness of the OLEDs in the organic light emitting display device.
In the prior art, with the continuity of using the organic light emitting display device, the organic light emitting diodes in pixel circuits may degrade to different degrees after the organic light emitting display device has illuminated over a long time, thereby causing an increase in the threshold voltage of the OLED. Due to such increase of the threshold voltage of the OLED, the current flowing through the OLED is reduced under the effect of the same driving voltage, thus the illumination brightness of the OLED is decreased, so that the display quality of the organic light emitting display device is decreased and the service life of the organic light emitting display device is further shortened.